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(No Model.)

S. GHADWIGK. TELEPHONBIRANSMITTER.

,676. Patented A r. 8, 1884.

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ArnNr SAGER- GHADW'IGK, OF PHILADELPHIA, PENNSYLVANIA, ASSIGXOB OF ONE- HALF TO E. V. MAQHETTE, OF SAME PLACE.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 296,676, dated April 8. 1884.

Application filed June 9, 1883. (No model.)

To all whom it may concern:

Be'it known that I, SAGER CHADWICK, of the city of Philadelphia, county of Philadelphia, and State of Pennsylvania, have in- 5 vented an Improvement in Telephone-Transmitters, of which the following is a specification.

My invention has reference to telephonetransmittcrs; and it consists in a flexible dia phragm, preferably of hardened gelatine, provided with a contact-point, and combined with a contact-block of prepared gelatine, and in details of construction fully set forth in the following specification and shown in the ac- I 5 companying drawing, which forms part thereof.

The object of my invention is to provide a transmitting-telephone with an extremelysensitive contact mechanism and diaphragm, whereby the tension of the current may be more efi'ectually varied and articulation be more perfect.

In the drawing is shown a sectional elevation of my improved telephone-transmitter.

A is the frame.

B is the diaphragm, which may be made of metal, parchment, gelatine, preferably hardened, or any flexible material. Gelatine, being the most sensitive, is preferred.

dissolving gelatin e and treating it with ch romic acid or any of the chromates, and exposing the preparation, after being run into thin sheets, to light. Any desired thickness may thus be had, and to make the diaphragm more sensitive it maybe placed upon the transmitterframe while still somewhat moist or pliable, and, after being clamped thereon, allowed to dry, when it becomes extremelytight. Parchment, being nothing more than one form of gelatine, may be treated with chromic acid or the chromates and hardened in the same mannor as above specified; hence my invention also comprehends hardened parchment under the term hardened gelatine.

To the center of the diaphragm I secure a conical conducting-piece, 0, preferably of copper, the point of which extends from the diaphragm B.

D is a block or piece of gelatine, preferably what is known as high-temperature gela- The hardened gelatine diaphragm may be prepared by.

tine, and which is a hard quality of same mixed with glycerine, molasses, glucose, canesugar, or their equivalent, to form what is substantially similar to printers rollers, the glycerine therein keeping it in a moist condition, and while moist it is a comparatively good conductor of electricity. This 'gclatine block D is secured upon the vertical metal support E, connected by wire 13 to one pole of the primary wire of the usual induction-coil, G. The

wire'F connects the other pole of the primary wire with the contact-piece C.

H is the local battery, and I is the line through the secondary wire of the inductioncoil. If desired, both the contacts C and D may be made of gelatinc.

The operation is as follows: The diaphragm B is vibrated in accordance with the articulation. This causes the conical point C to enter more or less into the soft gelatine block D, causing varying amounts of surface to come into contact with the gelatine, and also varying its distance from the metal support E, thereby varying the resistance in the local circuit. Owing to the peculiar properties of gelatine when in this condition, the varying resistance is greatly amplified over that when carbon contacts are used, thus producing more clear and louder articulations in the receiver than is possible with carbon transmitters.

If desired, a case, J, may be placed around the gelatine contact to preserve it from too sudden variations in the temperature of the atmosphere, dust, &c.

I do not limit myself to the exact construction shown, as it may be modified without departing from my invention.

Having now described myinvention, what I claim as new, and desire to secure by Letters Patent, is-- l. A tclephonetransmitter having a con tact-block made of gelatine prepared with glyccrine or its described equivalent, substantially as described.

2. The combination of diaphragm B, coni- 5 cal contact 0, gelatinous composition block D, substantially as described, and metal support E, substantially as and for the purpose specified.

3. The combination of diaphragm B, conical contact 0, gelatinous composition block D, substantially as described, metal support E, and case J, substantially as and for the purpose specified.

4. A telephone-transmitter provided with a diaphragm made of gelatine, substantially as described.

5. The combination of gelatine diaphragm B, oontactpoint 0, prepared gelatine block D, substantially as described, metal support 10 E, and case J.

In testimony of which invention I hereunto set my hand.

SAGER CHADWVIGK.

Witnesses:

R. M. HUNTER, FRANCIS S. BROWN. 

